Auger electron spectroscopy as a real-time compositional probe in molecular beam epitaxy

Abstract

We describe the use of dynamical Auger electron spectroscopy to determine the stoichiometry of compound materials grown by molecular beam epitaxy (MBE). A small, high-speed Auger electron spectrometer has been incorporated into a custom-built MBE system in such a way that Auger measurements can be carried out during growth without blocking any of the atomic or molecular beams. The same electron beam used to generate reflection high-energy electron diffraction patterns is used to excite Auger transitions. The sensitivity of the method is determined by measuring and modeling the angular dependence of Mg KLL and O KLL Auger emission from clean MgO(001). We have tested the technique for MgO(001) homoepitaxy and heteroepitaxy of CrxMo1−x on MgO(001). With careful calibration, film composition can be rapidly determined to within a few percent both during and after growth by this method. In addition to the successes achieved with the technique thus far, potential difficulties are discussed.